Identification of Genes inCandida glabrataConferring Altered Responses to Caspofungin, a Cell Wall Synthesis Inhibitor

Cultures of sensitive stains of Staphylococcus aureus were fixed with osmium tetroxide after 1–5 hours' exposure to various does of pencillin and were embedded in methacrylate for sectioning and electron microscopy. They were compared with untreated, control cultures. The contrast of the cell wall material was untreated, control cultures. The contrast of the cell wall material was increased, by cutting the section of lanthanum nitrate.The cells increased in size and the surrounding cell wall was thinner than normal. The main lesions appeared in the developing cell wall septa, which showed a loss in density and gross irregularity of shape. Some questionable inclusions were seen in the cytoplasm. Lysis was prevented in a medium containing 0.3 M sucrose and the stable spheroplasts retained a recognizable cell wall after 24 hours' exposure to penicillin. However, the septa could not be demonstrated in the cells treated in sucrose medium.Two resistant strains were exposed to penicillin. In one, the cells showed no morphological effects; in the other, there was temporary damage to the cell septa with complete recovery.The observations support the hypothesis that penicillin interferes with the synthesis of a cell wall component and indicate that the main point of cell wall synthesis is at the site of septum formation.

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High-Level β-Lactam Resistance and Cell Wall Synthesis Catalyzed by the mecA Homologue of Staphylococcus sciuri Introduced into Staphylococcus aureus

Journal of Bacteriology ◽

10.1128/jb.187.19.6651-6658.2005 ◽

2005 ◽

Vol 187 (19) ◽

pp. 6651-6658 ◽

Cited By ~ 10

Author(s):

Anatoly Severin ◽

Shang Wei Wu ◽

Keiko Tabei ◽

Alexander Tomasz

Keyword(s):

Staphylococcus Aureus ◽

Cell Wall ◽

High Performance ◽

Protein Product ◽

Spectrometric Analysis ◽

Cell Wall Synthesis ◽

Absolute Dependence ◽

A Cell ◽

High Concentrations ◽

High Level

ABSTRACT A close homologue of mecA, the determinant of broad-spectrum β-lactam resistance in Staphylococcus aureus was recently identified as a native gene in the animal commensal species Staphylococcus sciuri. Introduction of the mecA homologue from a methicillin-resistant strain of S. sciuri into a susceptible strain of S. aureus caused an increase in drug resistance and allowed continued growth and cell wall synthesis of the bacteria in the presence of high concentrations of antibiotic. We determined the muropeptide composition of the S. sciuri cell wall by using a combination of high-performance liquid chromatography, mass spectrometric analysis, and Edman degradation. Several major differences between the cell walls of S. aureus and S. sciuri were noted. The pentapeptide branches in S. sciuri were composed of one alanine and four glycine residues in contrast to the pentaglycine units in S. aureus. The S. sciuri wall but not the wall of S. aureus contained tri- and tetrapeptide units, suggesting the presence of dd- and ld-carboxypeptidase activity. Most interestingly, S. aureus carrying the S. sciuri mecA and growing in methicillin-containing medium produced a cell wall typical of S. aureus and not S. sciuri, in spite of the fact that wall synthesis under these conditions had an absolute dependence on the heterologous S. sciuri gene product. The protein product of the S. sciuri mecA can efficiently participate in cell wall biosynthesis and build a cell wall using the cell wall precursors characteristic of the S. aureus host.

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A cell wall damage response mediated by a sensor kinase/response regulator pair enables beta-lactam tolerance

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1520333113 ◽

2015 ◽

Vol 113 (2) ◽

pp. 404-409 ◽

Cited By ~ 34

Author(s):

Tobias Dörr ◽

Laura Alvarez ◽

Fernanda Delgado ◽

Brigid M. Davis ◽

Felipe Cava ◽

...

Keyword(s):

Cell Wall ◽

Response Regulator ◽

Cell Envelope ◽

Normal Growth ◽

Cell Diameter ◽

Cell Wall Synthesis ◽

Beta Lactam ◽

Cell Wall Damage ◽

A Cell

The bacterial cell wall is critical for maintenance of cell shape and survival. Following exposure to antibiotics that target enzymes required for cell wall synthesis, bacteria typically lyse. Although several cell envelope stress response systems have been well described, there is little knowledge of systems that modulate cell wall synthesis in response to cell wall damage, particularly in Gram-negative bacteria. Here we describe WigK/WigR, a histidine kinase/response regulator pair that enablesVibrio cholerae, the cholera pathogen, to survive exposure to antibiotics targeting cell wall synthesis in vitro and during infection. Unlike wild-typeV. cholerae, mutants lackingwigRfail to recover following exposure to cell-wall–acting antibiotics, and they exhibit a drastically increased cell diameter in the absence of such antibiotics. Conversely, overexpression ofwigRleads to cell slimming. Overexpression of activated WigR also results in increased expression of the full set of cell wall synthesis genes and to elevated cell wall content. WigKR-dependent expression of cell wall synthesis genes is induced by various cell-wall–acting antibiotics as well as by overexpression of an endogenous cell wall hydrolase. Thus, WigKR appears to monitor cell wall integrity and to enhance the capacity for increased cell wall production in response to damage. Taken together, these findings implicate WigKR as a regulator of cell wall synthesis that controls cell wall homeostasis in response to antibiotics and likely during normal growth as well.

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An Alternative and Conserved Cell Wall Enzyme That Can Substitute for the Lipid II Synthase MurG

mBio ◽

10.1128/mbio.03381-20 ◽

2021 ◽

Vol 12 (2) ◽

Author(s):

L. Zhang ◽

K. Ramijan ◽

V. J. Carrión ◽

L. T. van der Aart ◽

J. Willemse ◽

...

Keyword(s):

Cell Wall ◽

Sequence Similarity ◽

Streptomyces Coelicolor ◽

Genomic Analysis ◽

Environmental Harm ◽

Cell Wall Synthesis ◽

Precursor Molecule ◽

Content Type ◽

Lipid Ii ◽

A Cell

ABSTRACT The cell wall is a stress-bearing structure and a unifying trait in bacteria. Without exception, synthesis of the cell wall involves formation of the precursor molecule lipid II by the activity of the essential biosynthetic enzyme MurG, which is encoded in the division and cell wall synthesis (dcw) gene cluster. Here, we present the discovery of a cell wall enzyme that can substitute for MurG. A mutant of Kitasatospora viridifaciens lacking a significant part of the dcw cluster, including murG, surprisingly produced lipid II and wild-type peptidoglycan. Genomic analysis identified a distant murG homologue, which encodes a putative enzyme that shares only around 31% amino acid sequence identity with MurG. We show that this enzyme can replace the canonical MurG, and we therefore designated it MglA. Orthologues of mglA are present in 38% of all genomes of Kitasatospora and members of the sister genus Streptomyces. CRISPR interference experiments showed that K. viridifaciens mglA can also functionally replace murG in Streptomyces coelicolor, thus validating its bioactivity and demonstrating that it is active in multiple genera. All together, these results identify MglA as a bona fide lipid II synthase, thus demonstrating plasticity in cell wall synthesis. IMPORTANCE Almost all bacteria are surrounded by a cell wall, which protects cells from environmental harm. Formation of the cell wall requires the precursor molecule lipid II, which in bacteria is universally synthesized by the conserved and essential lipid II synthase MurG. We here exploit the unique ability of an actinobacterial strain capable of growing with or without its cell wall to discover an alternative lipid II synthase, MglA. Although this enzyme bears only weak sequence similarity to MurG, it can functionally replace MurG and can even do so in organisms that naturally have only a canonical MurG. The observation that MglA proteins are found in many actinobacteria highlights the plasticity in cell wall synthesis in these bacteria and demonstrates that important new cell wall biosynthetic enzymes remain to be discovered.

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Bacterial Cell Wall Synthesis: New Insights from Localization Studies

Microbiology and Molecular Biology Reviews ◽

10.1128/mmbr.69.4.585-607.2005 ◽

2005 ◽

Vol 69 (4) ◽

pp. 585-607 ◽

Cited By ~ 375

Author(s):

Dirk-Jan Scheffers ◽

Mariana G. Pinho

Keyword(s):

Cell Wall ◽

Bacterial Cell ◽

Cell Shape ◽

Fluorescent Protein ◽

Model Organisms ◽

Live Cells ◽

Cell Wall Synthesis ◽

A Cell ◽

Green Fluorescent ◽

Bacterial Cell Shape

SUMMARY In order to maintain shape and withstand intracellular pressure, most bacteria are surrounded by a cell wall that consists mainly of the cross-linked polymer peptidoglycan (PG). The importance of PG for the maintenance of bacterial cell shape is underscored by the fact that, for various bacteria, several mutations affecting PG synthesis are associated with cell shape defects. In recent years, the application of fluorescence microscopy to the field of PG synthesis has led to an enormous increase in data on the relationship between cell wall synthesis and bacterial cell shape. First, a novel staining method enabled the visualization of PG precursor incorporation in live cells. Second, penicillin-binding proteins (PBPs), which mediate the final stages of PG synthesis, have been localized in various model organisms by means of immunofluorescence microscopy or green fluorescent protein fusions. In this review, we integrate the knowledge on the last stages of PG synthesis obtained in previous studies with the new data available on localization of PG synthesis and PBPs, in both rod-shaped and coccoid cells. We discuss a model in which, at least for a subset of PBPs, the presence of substrate is a major factor in determining PBP localization.

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